JP7366504B2 - How to divide the workpiece - Google Patents

Description

The present invention relates to a method for dividing a workpiece, which is used when dividing a plate-shaped workpiece.

BACKGROUND ART In electronic devices such as mobile phones and personal computers, a device chip that includes devices such as electronic circuits has become an essential component. For example, device chips are made by dividing the surface of a wafer made of a semiconductor material such as silicon into multiple areas along dividing lines (street), forming devices in each area, and then cutting the wafer along the dividing lines. Obtained by dividing.

When dividing a wafer into a plurality of device chips, a cutting device equipped with an annular cutting blade made of abrasive grains such as diamond hardened with a binder such as metal or resin is used. By rotating the cutting blade at high speed and cutting into the wafer along the planned dividing line, the wafer can be divided into multiple device chips. The wafer after being divided is cleaned by a cleaning unit included in the cutting device (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2006-339435

By the way, when dividing a plate-shaped workpiece such as a wafer using the above-mentioned cutting device, a protective tape is attached to the back side of the workpiece, and the workpiece is separated through this tape. The workpiece is often cut with the device exposed by holding it. However, with this method, scraps and dust generated by cutting tend to stick to devices and the like.

Debris and dust stuck to the device are not completely removed even if the workpiece is washed later, resulting in defects. On the other hand, it is also conceivable to attach a tape to the front side of the workpiece and cut the workpiece with the back side exposed. However, in this case, the adhesive of the tape may remain on the device on the front side, causing a defect.

The present invention has been made in view of these problems, and its purpose is to provide a new method for dividing a workpiece that can reduce the possibility of device contamination when dividing the workpiece. It is to provide.

According to one aspect of the present invention, a workpiece used when dividing a workpiece is provided with a recess in which a device is formed on the bottom surface defined by a dividing line, and a ring-shaped reinforcement portion surrounding the recess. A method for dividing a workpiece, the step of attaching a first tape to the reinforcing portion without contacting the bottom surface of the recess, and sealing the space inside the recess with the first tape; and the reinforcing step. a starting point region forming step of forming a starting point region to be a starting point of division on the dividing line from the side opposite to the first tape of the workpiece to which the first tape is attached; and a second tape. a tape reapplying step of affixing the first tape to the surface side of the workpiece and peeling off the first tape from the reinforcing portion, and expanding the second tape to cover the workpiece starting from the starting point area. A method for dividing a workpiece is provided, comprising: dividing the workpiece.

In one aspect of the present invention, in the starting point region forming step, a cutting blade equipped with a cutting edge containing abrasive grains is rotated to cut into the surface side of the workpiece to form a groove that will be a starting point of division. It may be formed on the planned dividing line.

Further, in one aspect of the present invention, in the starting point region forming step, a laser beam having a wavelength that is absorbed by the workpiece is irradiated onto the surface side of the workpiece to form a groove that is a starting point of the division. It may form on the scheduled line.

In the method for dividing a workpiece according to one aspect of the present invention, the first tape is attached to the reinforcing portion without contacting the bottom surface of the recess where the device is formed, and the space inside the recess is sealed with the first tape. Later, since the starting point area that is the starting point of division is formed from the side opposite to the first tape, the starting point area is formed on the workpiece while keeping the space inside the recess where the device is placed in a clean state. can.

That is, it is possible to prevent debris and dust generated when forming the starting point region from adhering to the device. Further, the adhesive of the tape does not remain on the device, unlike when the tape is applied to the region of the workpiece where the device is formed. Therefore, according to the method for dividing a workpiece according to one aspect of the present invention, the possibility that a device will be contaminated when dividing a workpiece can be suppressed to a low level.

FIG. 1 is a perspective view schematically showing a workpiece. FIG. 2 is a cross-sectional view schematically showing a workpiece to which the first tape is attached. FIG. 3 is a cross-sectional view schematically showing how a groove serving as a starting point for division is formed in a workpiece. FIG. 4 is a cross-sectional view schematically showing a workpiece in which grooves are formed. FIG. 5 is a cross-sectional view schematically showing the workpiece to which the second tape is attached. FIG. 6 is a cross-sectional view schematically showing the workpiece from which the first tape has been peeled off. FIG. 7 is a cross-sectional view schematically showing how the workpiece is divided.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a workpiece 11 to be divided by the workpiece dividing method according to the present embodiment. The workpiece 11 is, for example, a disk-shaped wafer formed using a semiconductor such as silicon, and has a first surface (front surface) 11a and a second surface (back surface) located on the opposite side to the first surface 11a. ) 11b.

The first surface 11a and the second surface 11b are both generally flat and generally parallel to each other. A recess 13 having a circular shape when viewed from the first surface 11a is provided in a central region of the workpiece 11 on the first surface 11a side. That is, this recess 13 opens to the first surface 11a, and the space inside the recess 13 is connected to the space outside the workpiece 11 on the first surface 11a side.

A ring-shaped region surrounding the recess 13 of the workpiece 11 becomes a reinforcing portion 15 that supplements the strength of the workpiece 11 that is insufficient due to the recess 13. The thickness of the ring-shaped reinforcing portion 15 (the distance between the first surface 11a and the second surface 11b) is larger than the distance between the bottom surface 13a of the recess 13 and the second surface 11b.

The bottom surface 13a of the recess 13 is divided into a plurality of regions by a plurality of dividing lines 17 that intersect with each other, and a device 19 such as an IC (Integrated Circuit) is formed in each region. Note that there are no restrictions on the material, shape, structure, size, etc. of the workpiece 11. For example, a substrate formed using other semiconductors, ceramics, resins, metals, etc. can also be used as the workpiece 11. Similarly, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device 19.

Such a workpiece 11 is made by thinning a central region of a wafer or the like having two planes that are generally parallel to each other by a method such as etching or grinding to form a recess 13, and a bottom surface 13a of the recess 13. This can be obtained by forming the device 19 in the same manner. By using the workpiece 11 having the recess 13 and the reinforcing part 15, it is possible to realize a method of dividing the workpiece in which the possibility of contamination of the device 19 is kept low. However, there are no particular restrictions on the method of obtaining this workpiece 11.

In the method for dividing the workpiece according to this embodiment, first, the space inside the recess 13 is sealed so that debris and dust generated when processing the workpiece 11 do not adhere to the device 19. Specifically, a tape (first tape) large enough to cover the recess 13 is attached to the first surface 11a side of the reinforcing part 15, and the space inside the recess 13 and the outside of the workpiece 11 are covered. Separate the space (taping step).

FIG. 2 is a cross-sectional view schematically showing the workpiece 11 to which the first tape 21 is attached. The first tape 21 includes a film-like base material layer and an adhesive layer that is provided on substantially the entire surface of one side of the base material layer and exhibits adhesive strength to the workpiece 11. The base layer of the first tape 21 is made of a material such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer of the first tape 21 is made of an acrylic or rubber material, for example. .

The first tape 21 is, for example, formed into a circular shape having a diameter comparable to the outer diameter of the first surface 11a (or second surface 11b) of the workpiece 11. When attaching the first tape 21 to the workpiece 11, the adhesive layer located on the outer circumference of the first tape 21 is brought into close contact with the first surface 11a of the reinforcing portion 15 of the workpiece 11.

More specifically, the first tape 21 is attached to the workpiece so that there is no gap between the first surface 11a of the reinforcing portion 15 and the adhesive layer of the first tape 21 in the entire circumferential direction of the workpiece 11. 11. As a result, the space inside the recess 13 is sealed with the first tape 21. However, the first tape 21 should not be brought into contact with the bottom surface 13a of the recess 13. This is because if the first tape 21 is brought into contact with the bottom surface 13a, there is a high possibility that the material (adhesive) constituting the adhesive layer of the first tape 21 will adhere to and remain on the device 19.

After attaching the first tape 21 to the reinforcing portion 15, from the second surface 11b side of the workpiece 11 (i.e., the surface opposite to the first tape 21), a groove (starting point region) that is the starting point of division is formed. is formed on the planned dividing line 17 (starting point region forming step). FIG. 3 is a cross-sectional view schematically showing how grooves 17a, which serve as starting points for division, are formed in the workpiece 11.

When forming the groove 17a in the workpiece 11, for example, a cutting device 2 shown in FIG. 3 is used. The cutting device 2 includes, for example, a chuck table (vacuum chuck) (not shown) having a generally flat holding surface suitable for holding the workpiece 11. This chuck table is connected to a rotational drive source such as a motor, and rotates around a rotation axis that is generally perpendicular to the above-mentioned holding surface. Further, the chuck table is supported by a ball screw type moving mechanism, and moves in a machining and feeding direction that is generally parallel to the above-mentioned holding surface.

A cutting unit 4 is arranged above the chuck table. The cutting unit 4 includes, for example, a spindle 6 having an axis substantially parallel to the holding surface of the chuck table and substantially perpendicular to the machining feed direction. A cutting blade 8 having a cutting edge containing abrasive grains is attached to one end of the spindle 6. A rotational drive source (not shown) such as a motor is connected to the other end of the spindle 6, and the cutting blade 8 attached to one end of the spindle 6 is rotated by the power of this rotational drive source.

The cutting unit 4 is supported by a ball screw type movement mechanism (not shown). The cutting blade 8 is moved by this movement mechanism in an indexing feed direction that is generally parallel to the holding surface of the chuck table and generally perpendicular to the machining feed direction, and in a vertical direction that is generally perpendicular to the holding surface. A nozzle (not shown) for supplying liquid (cutting fluid) such as water to the cutting blade 8 and the workpiece 11 is arranged on the side of the cutting blade 8 .

When forming the groove 17a, which is the starting point of division, on the planned division line 17, the base layer side of the first tape 21 attached to the workpiece 11 is brought into contact with the holding surface of the chuck table, and the chuck is A workpiece 11 is held on a table. That is, the workpiece 11 is held on the chuck table so that the second surface 11b side is exposed upward.

After the workpiece 11 is held by the chuck table, for example, the chuck table is rotated to make the desired dividing line 17 approximately parallel to the processing feed direction. Next, the chuck table and the cutting unit 4 are moved relatively to align the position of the cutting blade 8 above the extension line of this scheduled dividing line 17. Note that when confirming the position of the planned dividing line 17, it is preferable to take an image of the device 19 from the second surface 11b side using an infrared camera or the like. A mark indicating the planned dividing line 17 may be attached to the second surface 11b of the workpiece 11 or the like.

Further, the height of the cutting unit 4 with respect to the chuck table is adjusted so that the height of the lower end of the cutting blade 8 is lower than the height of the second surface 11b of the workpiece 11 and higher than the height of the bottom surface 13a. Then, while rotating the cutting blade 8, the chuck table is moved in the processing feed direction to cause the cutting blade 8 to cut into the workpiece 11. When cutting the cutting blade 8 into the workpiece 11, liquid is supplied to the cutting blade 8 and the workpiece 11 from a nozzle.

Thereby, the rotated cutting blade 8 can be cut into the second surface 11b side of the workpiece 11 to form the groove 17a on the target dividing line 17. In this embodiment, the height of the lower end of the cutting blade 8 is made higher than the height of the bottom surface 13a, so the formed groove 17a does not penetrate the workpiece 11. In other words, the formed groove 17a does not open to the bottom surface 13a.

Therefore, debris and dust generated when forming the groove 17a do not enter the space inside the recess 13 and adhere to the device 19. The same procedure is repeated until the grooves 17a are formed on all the planned dividing lines 17. FIG. 4 is a cross-sectional view schematically showing the workpiece 11 in which the groove 17a is formed.

Note that when forming the groove 17a in the workpiece 11, it is necessary to form the groove 17a not only in the area that overlaps the bottom surface 13a when viewed from the second surface 11b side (the area inside the reinforcing portion 15), but also in the area that overlaps the bottom surface 13a when viewed from the second surface 11b side. It is desirable to form the groove 17a also in the region outside the bottom surface 13a (reinforcement portion 15). Thereby, the entire workpiece 11 including the reinforcing portion 15 can be divided appropriately.

In this case, the groove 17a of the reinforcing part 15 may be formed deeper than the groove 17a in the area inside the reinforcing part 15. The deep groove 17a of the reinforcing portion 15 can be formed, for example, by a method called a chopper cut in which a rotating cutting blade 8 is cut from directly above. Note that if the reinforcing portion 15 is removed before dividing the workpiece 11, it is not necessary to form the groove 17a in the area outside the bottom surface 13a.

After forming the groove 17a that becomes the starting point of division in the workpiece 11, another tape (second tape) is attached to the second surface 11b side of the workpiece 11, and the first tape 21 is attached to the reinforcing part 15 ( The tape is peeled off from the first surface 11a) of the workpiece 11 (tape replacement step). FIG. 5 is a cross-sectional view schematically showing the workpiece 11 to which the second tape 23 is attached, and FIG. 6 is a cross-sectional view schematically showing the workpiece 11 from which the first tape 21 has been peeled off. be.

The structure and material of the second tape 23 are, for example, the same as those of the first tape 21. That is, the second tape 23 includes a film-like base material layer and an adhesive layer that is provided on substantially the entire one surface of the base material layer and exhibits adhesive strength to the workpiece 11. However, this second tape 23 is formed to be larger than the outer edge of the first surface 11a (or second surface 11b) of the workpiece 11.

When attaching the second tape 23 to the workpiece 11, the adhesive layer of the second tape 23 is brought into close contact with the entire second surface 11b of the workpiece 11, as shown in FIG. In this way, by applying the second tape 23 to the entire second surface 11b, when the second tape 23 is expanded, force is applied to the entire second surface 11b, and the workpiece 11 can be properly moved. It becomes possible to divide. After attaching the second tape 23 to the workpiece 11, the first tape 21 is peeled off from the reinforcing portion 15, as shown in FIG.

Note that in this embodiment, the first tape 21 is peeled off from the reinforcing part 15 after the second tape 23 is attached to the workpiece 11; A second tape 23 may be attached to the workpiece 11. Further, a ring-shaped frame may be fixed to the second tape 23 so that the workpiece 11 is accommodated in an opening of the ring-shaped frame having an opening larger than the workpiece 11.

After attaching the second tape 23 to the workpiece 11 and peeling off the first tape 21 from the reinforcing portion 15, the second tape 23 is expanded to divide the workpiece 11 starting from the groove 17a (dividing step). ). FIG. 7 is a cross-sectional view schematically showing how the workpiece 11 is divided. When dividing the workpiece 11, for example, an expansion device including a cylindrical expansion drum having a diameter larger than the workpiece 11 is used.

Specifically, the expansion drum of the expansion device and the second tape 23 are moved relatively, so that the end surface of the expansion drum corresponding to the bottom surface of the cylinder abuts against the base material layer of the second tape 23. As a result, the second tape 23 is expanded in the radial direction of the expansion drum (that is, isotropically), and the force applied to the workpiece 11 as the second tape 23 expands causes the workpiece 11 to be expanded. It is divided into a plurality of chips 31.

Note that there is no restriction on the specific method for dividing the workpiece 11. In this embodiment, the workpiece 11 is divided by isotropically expanding the second tape 23 using an expansion device equipped with a cylindrical expansion drum. The workpiece 11 can also be divided by expanding the second tape 23 in the vertical direction.

As described above, in the method for dividing a workpiece according to the present embodiment, the first tape 21 is attached to the reinforcing part 15 without contacting the bottom surface 13a of the recess 13 on which the device 19 is formed, and After sealing the space with the first tape 21, a groove (starting point region) 17a that becomes the starting point of division is formed from the second surface 11b side opposite to the first tape 21, so that the recess 13 where the device 19 is placed is formed. The groove 17a can be formed in the workpiece 11 while keeping the inner space clean.

That is, it is possible to prevent debris and dust generated when forming the grooves 17a from adhering to the device 19. Furthermore, the adhesive of the tape does not remain on the device 19 unlike when the tape is attached to the region of the workpiece 11 where the device 19 is formed. Therefore, according to the workpiece dividing method according to the present embodiment, the possibility that the device 19 will be contaminated when dividing the workpiece 11 can be suppressed to a low level.

Note that the present invention is not limited to the description of the embodiments described above, and can be implemented with various modifications. For example, in the embodiment described above, the workpiece 11 having the recesses 13 having a circular shape when viewed from the first surface 11a side is divided, but in a similar manner, the shape when viewed from the first surface 11a side is divided. A workpiece 11 having a non-circular recess 13 can be divided.

Furthermore, in the embodiment described above, the cutting blade 8 equipped with a cutting edge containing abrasive grains is used to form the groove (starting point region) 17a, which is the starting point of dividing, in the dividing line 17 of the workpiece 11. By ablation processing in which the second surface 11b side of the workpiece 11 is irradiated with a laser beam with a wavelength that is absorbed by the workpiece 11, a groove (starting point region) that becomes the starting point of division is formed on the planned division line of the workpiece 11. 17 (starting point region forming step).

In this case, for example, a chuck table (vacuum chuck) with a generally flat holding surface suitable for holding the workpiece 11 and a laser oscillator that generates a laser beam with a wavelength that is absorbed by the workpiece 11 are required. A laser processing apparatus is used, which includes a laser processing unit equipped with a condenser such as a lens for condensing a laser beam, and a condenser such as a lens for condensing a laser beam.

In addition, the structure, method, etc. according to the embodiments described above can be modified and implemented as appropriate without departing from the scope of the objective of the present invention.

11: Workpiece 11a: First surface (surface)
11b: Second side (back side)
13: Recessed portion 13a: Bottom surface 15: Reinforcement portion 17: Planned dividing line 17a: Groove 19: Device 21: First tape 23: Second tape 31: Chip 2: Cutting device 4: Cutting unit 6: Spindle 8: Cutting blade

Claims (3)

A method for dividing a workpiece, which is used when dividing a workpiece, the workpiece comprising a recess in which a device is formed on the bottom surface divided by a planned dividing line, and a ring-shaped reinforcing part surrounding the recess, the method comprising:
a tape applying step of applying a first tape to the reinforcing portion without contacting the bottom surface of the recess, and sealing the space inside the recess with the first tape;
a starting point region forming step of forming a starting point region to be a starting point of division on the dividing line from the side opposite to the first tape of the workpiece to which the first tape is attached to the reinforcing portion;
a tape reapplying step of attaching a second tape to the surface side of the workpiece and peeling off the first tape from the reinforcing portion;
A method for dividing a workpiece, comprising the step of expanding the second tape and dividing the workpiece starting from the starting point region. In the starting point region forming step, a cutting blade equipped with a cutting edge containing abrasive grains is rotated to cut into the surface side of the workpiece to form a groove that will be a starting point for dividing at the planned dividing line. The method for dividing a workpiece according to claim 1, characterized in that: The starting point region forming step is characterized by irradiating the surface side of the workpiece with a laser beam having a wavelength that is absorbed by the workpiece to form a groove that will be a starting point for division at the planned dividing line. The method for dividing a workpiece according to claim 1.

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